Work holding device



Jami, 1949. I EMRIICH 2,457,311

WORK HOLDING DEVICE Filed May 22; 1945 IN V EN TOR.

ATTORNEY Patented Jan. 4, 1949 UNI] TED .S TATES PATEN T F F JICE WORKHOLDING DEVICE Albert F. Emrich, Valley Stream, N. Application May 22,1945, Se1' ial-N0. 595, 219

(Granted underthe act (if 'March "3 1888, as amended April 30, 1928-;370 0. G.- 7

1 Claim.

This invention relates to a work-holding device, especially useful forholding small optical mirrors during work upon a section of a surfacethereof.

The horizon mirrors of sextants, for example, are small, flat,transparent plates, one surface of which is silvered over half its area,the remainder of the area being clear and transparent. The line ofdemarcation between the silvered and the clear areas must be straightand sharp. Hitherto one way of attaining this result has been to silverthe entire surface, scribe a straight line through the silver layer atthe desired point, and remove the silver from the area to be left clearby scraping carefully up to the line. The manual performance of such anoperation is time-consuming and wasteful, involving as it doesconsiderable spoilage.

It is an object of this invention to provide a work-holding device thatwill protect a part of the surface of an object while the remainder ofthe surface is being worked upon.

Another object is to provide a work-holding device that willsimultaneously clamp and hold a work piece and at the same time serve asa guide for the cutting tool so as to define a sharp line of demarcationupon a surface of the workpiece.

Other objects and advantages of this invention, as well as itsconstruction, arrangement and operation, will be apparent from thefollowing description and claim in connection with the accompanyingdrawing, in which,

Fig. 1 is an isometric view of the device of this invention, and

Fig. 2 is a central longitudinal section through the longitudinal axisof the device of Fig. 1, seen from the right hand side thereof.

it represents a base plate, upon which are mounted two parallel sideplates I2. Squaring plate 13 rests upon base platell and is containedbetween side plates l2. Locking screw i l extends through slot [5 insquaring plate l3, and is in threaded engagement with a hole providedfor that purpose in base plate ll.

Side plates 12 are provided with co-axial holes l6. Guide plate H isalso contained between side plates [2, and is rotatably mounted aboutthe axis of holes 16, said mounting being effected by cap screws, pinsor similar means extending from guide plate I! into holes Hi.

Pressure plate l8 extends across the tops of side plates !2 near theirforward end. In threaded engagement with a hole centrally located inpressure plate [8 is a pressure screw l9. Guide plate 1"! is secured tothe end of pressure screw I9 in any suitable manner, as by a flat headscrew 20, extending through guide plate I! and in threaded engagementwith a hole drilled into the end of pressure screw l 9. Pin 2| may beprovided to prevent rotation of fiat head screw 20 relative'to pressurescrew 19. Work piece 22 represents the article being worked upon.

The operation of the device is as follows. Squaring plate I3 is adjustedso that its forward edge is at the desired distance from the forwardedge of guide plate I1, and is locked in that position by locking screwl4. Work piece 22 is then placed upon base plate H, and an edge thereofforced against squaring plate 13. Pressure screw I9 is then turned sothat the forward edge of guide plate I! is brought into contact with thework piece 22, and tightened sufficiently to clamp the work piece 22firmly against the base plate II.

It will be apparent that squaring plate l3 and guide plate I1 arepreferably made of such a width as to constitute a close fit between theside plates l2, so as substantially to eliminate side play. The edges ofsquaring plate 13 and guide plate I! are made as straight and square aspossible, thus assuring that the forward edges of these parts will bestraight and parallel throughout their lengths. With an edge of workpiece 22 abutting squaring plate 13, the forward edge of guide plate l1will demarcate a line parallel to that edge of work piece 22. Theforward edge of guide plate I! is preferably beveled on the side awayfrom work piece 22, to facilitate access of tools to the line ofdemarcation defined on work piece 22 by the adjacent edge of guide plateI1.

Once squaring plate l3 has been accurately adjusted for a particularpiece of work, any number of successive pieces may be inserted andworked upon without further adjustment. Each work piece may be releasedand each successive work piece may be clamped in proper position bymerely turning pressure screw I9. With the work piece 22 firmly clampedin the device of this invention, the exposed surface may be freelyworked upon, with no possibility of the work inadvertently affecting theunexposed surface, and the line of division between the surface workedupon and the surface not worked upon will be sharp and straight.

In the event a line of demarcation is desired that is not straight, ornot parallel to an edge of the work, the clamping edge of guide plate I!may be made in any desired angular relationship with the sides of guideplate I 1. or be made in any arcuate or irregular shape, to conformtothe shape of the area of the work to be protected.

It is to be understood that various modifications and changes may bemade in this invention without departing from the spirit and scopethereof as set forth in the appended claim.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

A work holding device comprising a base plate and two parallel sideplates, a squaring plate slidably contained within said side plates andresting upon said base plate, said sliding plate being in slidable andlockable engagement with said base plate, a clamping plate containedwithin said side plates and rotatably mounted about an axis normal tosaid side plates, said axis being spaced above said base platesuificiently to permit the clamping portion of said clamping plate to benearer said base plate than other portions of said clamping plate are,whereby said clamping plate may be brought to bear on work less hig thansaid plate and positioned on said has against said squaring plate, andadjustable means for moving the said clamping portion of said clampingplate into and out of proximity with said base plate.

ALBERT F. EMRICH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Hoefer June 9, 1885 Blackiston Dec. 31,1912 Number

